Yeah we will adapt, but not fast enough.
Third world nations will suffer. Some might die. Maybe many. But humanity will adapt. We might lose a few hundred million in the next few decades until their folks find new places to live, and we westerners will suffer an influx of refugees, and we'll be just fine once again.
The population of the planet will continue growing to about 20 billion during the worst of the climate change. And we'll be without ice caps. And we'll be fine.
Healthy skepticism is great, but personally I'd rather not our entire species die off because a majority of people assume we will be fine!
> And we'll be fine.
Maybe we should then consider how to prevent hundreds of millions of deaths in the meantime? Like, the holocaust didn't lead to the extinction of humans as a whole, but there's a good amount of literature around what should've been done differently to prevent it in the first place, and that's an order of magnitude fewer deaths than what you're forecasting.
The really wealthy westerners are spending their money inventing ways to leave Earth. That might be a clue to whether or not they believe aircon and bottled water is going to be enough to save their way of life.
On what basis do you believe the population will hit 20B, especially with birth rates plummeting to near-replacement levels all around the world? What countries are going to go backwards, and why?